Performance Analysis and Optimization of NOMA With HARQ for Short Packet Communications in Massive IoT

In this article, we consider the massive nonorthogonal multiple access (NOMA) with a hybrid automatic repeat request (HARQ) for short packet communications. To reduce latency, each user can perform one retransmission provided that previous was not decoded successfully. The system performance is evaluated both coordinated and uncoordinated transmissions. We first develop Markov model (MM) to analyze dynamics characterize error rate (PER) throughput of in scenario. power levels are then optimized two scenarios, including constrained reliability scenarios. A simple yet efficient dynamic cell planning also designed Numerical results show NOMA-HARQ limited number retransmissions achieve desired level guaranteed latency using proper control strategy. achieves higher compared orthogonal scheme HARQ under same average received constraint at base station.